﻿using UnityEngine;
using System.IO;
using System.Collections;

public class WAV  {

	// convert two bytes to one float in the range -1 to 1
	static float bytesToFloat(byte firstByte, byte secondByte) {
		// convert two bytes to one short (little endian)
		short s = (short)((secondByte << 8) | firstByte);
		// convert to range from -1 to (just below) 1
		return s / 32768.0F;
	}

	static int bytesToInt(byte[] bytes,int offset=0){
		int value=0;
		for(int i=0;i<4;i++){
			value |= ((int)bytes[offset+i])<<(i*8);
		}
		return value;
	}

	private static byte[] GetBytes(string filename){
		return File.ReadAllBytes(filename);
	}
	// properties
	public float[] LeftChannel{get; internal set;}
	public float[] RightChannel{get; internal set;}
	public int ChannelCount {get;internal set;}
	public int SampleCount {get;internal set;}
	public int Frequency {get;internal set;}

	// Returns left and right double arrays. 'right' will be null if sound is mono.
	public WAV(string filename):
	this(GetBytes(filename)) {}

	public WAV(byte[] wav){

		// Determine if mono or stereo
		ChannelCount = wav[22];     // Forget byte 23 as 99.999% of WAVs are 1 or 2 channels

		// Get the frequency
		Frequency = bytesToInt(wav,24);

		// Get past all the other sub chunks to get to the data subchunk:
		int pos = 12;   // First Subchunk ID from 12 to 16

		// Keep iterating until we find the data chunk (i.e. 64 61 74 61 ...... (i.e. 100 97 116 97 in decimal))
		while(!(wav[pos]==100 && wav[pos+1]==97 && wav[pos+2]==116 && wav[pos+3]==97)) {
			pos += 4;
			int chunkSize = wav[pos] + wav[pos + 1] * 256 + wav[pos + 2] * 65536 + wav[pos + 3] * 16777216;
			pos += 4 + chunkSize;
		}
		pos += 8;

		// Pos is now positioned to start of actual sound data.
		SampleCount = (wav.Length - pos)/2;     // 2 bytes per sample (16 bit sound mono)
		if (ChannelCount == 2) SampleCount /= 2;        // 4 bytes per sample (16 bit stereo)

		// Allocate memory (right will be null if only mono sound)
		LeftChannel = new float[SampleCount];
		if (ChannelCount == 2) RightChannel = new float[SampleCount];
		else RightChannel = null;

		// Write to double array/s:
		int i=0;
		while (pos < wav.Length) {
			LeftChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
			pos += 2;
			if (ChannelCount == 2) {
				RightChannel[i] = bytesToFloat(wav[pos], wav[pos + 1]);
				pos += 2;
			}
			i++;
		}
	}

	public override string ToString ()
	{
		return string.Format ("[WAV: LeftChannel={0}, RightChannel={1}, ChannelCount={2}, SampleCount={3}, Frequency={4}]", LeftChannel, RightChannel, ChannelCount, SampleCount, Frequency);
	}
}